What kind of practices are you referring to? Care to direct an over-worrier in this direction?
I can recommend books. The kind of practices are anything that shifts the attention outward, so that eventually whatever it is that finds the noise inside the head such a pressing concern lets up and loses interest in that noise and the noise quiets down.
After years of trying sitting meditation on and off, I've had the most fun with Douglas Harding's "headless way" experiments. Fun is good motivation, and quick and notable results are too.
"Headless way", "headlessness". Sounds damn bizarre, right? But it's just "test this and see if it isn't your experience" experiments. My mention of "increasing curiosity and wonder" was specifically my response to working through
this book. However, some people react with "So what? I'm (intellectually) aware this stuff and it does nothing for me", so you're mileage may vary.
It's got Sam Harris's endorsement if that helps. He said in a podcast he finds "how Douglas Harding and Richard Lang talk about 'seeing' is thrilling". Or start with Harris's
Waking Up. I only skimmed it, but I saw there are a few suggested meditations mixed in with the jibber-jabber about science and his opinions on things.
Acceptance and Commitment Therapy has "defusion" techniques. This page repeats what I've been saying, but makes the point clearer:
http://anxietyhappens.com/AcceptanceCommitment/acceptance.htm#you_are_not_your_anxiety
For books with defusion and other "psychological tricks", I only ever read Russ Harris' The Happiness Trap. But Chad LeJeune's
The Worry Trap looks more specific to the topic.
ACT adds to defusion some techniques for defining one's values and setting goals to get them done without stressing. It's called Acceptance
and Commitment Therapy for this reason. You said you can resolve worry by doing the thing you're worried about. That's different from worrying over things you cannot do anything about. So, maybe there's procrastination mixed in? If so then ACT addresses this too.
Here's an example defusion technique. Say maybe there's an internal voice (and if you're one of those persons who think they "don't hear voices" then you can, in imagination, give the distressing feeling a voice and listen to what it's saying). But say there's a critical voice inside that is niggling at you, inducing stress, and maybe it goes something like this: "Do it, get it done, you're lazy, things are going to shit cuz of what a lay-about you are!" This sort of thing can be defused by giving it Donald Duck's voice to take the wind out of its sails. That makes it easy to dismiss the pressure to "hurry and get it done!"
But if you pick only one book, pick the one about the headless way! Make it fun and lose your head and how filled-up with thinking, thinking, thinking it is.
Or buy nothing and just sit and meditate. No need to sit in a lotus pose, any attentive posture (non-conducive to sleep) is fine. There's no "must" pressure to perform; it's a vacation from mentation and not a chore. Many people complain "I sit there and I can't concentrate! It's just seconds and I get distracted and I have to start all over!" But however many the distracted moments, becoming mindful of them and gently returning to attention is a perfect performance. The only way to fuck up is to get judgmental and think "I'm screwing this up!" And if that happens,
be dispassionately mindful of your mind doing that... and there again it's success! And this way eventually the mind learns to let unhelpfully distressing thoughts "come and go" while staying calm(er).